It's my novice patent-drafter understanding that independent claims (especially the first one) should be as broad as possible without being so broad that as to easily negated by prior art of any kind – whether currently patented, previously patented, or never patented. So, some more narrow specifications (that might have originally been planned as dependent claim statements) may need to be pulled into the independent claim in order to set it apart. What's puzzling me a bit is, how far to go with that? Should I add what seems to be "just enough," or do I play it safer by pulling in more than one of what (I think) are unique distinguishing features? And is there any practical guideline for how complicated an independent claim can be? (referring specifically to how many indented statements are added following a "comprising" statement)
There are two forces at play here. For one, you want your claim as broad as possible - simply because the broader the claim, the broader your protection. On the other hand, the examiner, in combination with the prior art has a certain limit of what they will allow.
So the "perfect" broadness of your claim would be to exactly hit the limit of what is allowable.
The cheapest and fastest prosecution would be to start with only allowable claims.
The problem is, you cannot (!) know exactly what claim will be accepted and when it is too broad. So you play a kind of guessing game with the examiner. You start your claim at a certain level of broadness where you are sure it's outside of the allowable, but not by far and then take narrowing steps until arriving at some dependent claim which is certainly allowable.
You submit that for examination and the examiner will hopefully hint to you, where the border between allowable and not allowable lies. You then iteratively try to get as close as possible.
The problem here is, if you iterate into the allowable part, your patent passes and you can't go back - so you have to approach this border from the outside, overstepping it only a little bit at the end.
If all goes well, after a few office actions you have a reasonably broad patent, didn't waste too much time/money and everyone is happy. If your patent passes with the first claims you submit, they were too narrow.
As to how complicated a claim can be - complicated normally means narrow, it can be as complicated/narrow as you want, but the thing is, you don't want that.